There are already many of such chains on the market and described in patent and other literature. This invention is concerned with chains of the type shown in my U.S. Pat. No. 4,106,542 comprising links parallel to the surface of the tyre, known as "web links" or "connectors", and links generally perpendicular to the surface, known as "wearing links" or "wearing plates". In one known type of chain the connectors are annular links or loops and the wearing plates are rectangular plates having two holes or a slot, the wearing plates being arranged in an array interconnected by the connectors. For strength and easier manufacture, two holes are preferred to a single slot. Usually three or four wearing plates are connected to each connector. The chain has a tread portion and two flanking side-wall portions for fixing the chain to a tyre and, sometimes, for providing protection.
As is to be expected the quality of the chain is mostly determined by the wearing plates which, for this reason, have been made of a variety of alloy steels with through-hardening or case-hardening (carburising) as is appropriate. These plates are normally about 12 to 16 mm thick, depending on the type and size of chain to be formed. Because of the thickness of the material used for the plates they present problems to the manufacturer in forming the plates and providing them with a suitable and consistent hardness for abrasion resistance while not being brittle and likely to break under the repeated shocks of high force to which they are subject.